1. Field of the Invention
This invention relates to a device for moving a slidable body forward or backward and a method of controlling the position of the slidable body. More particularly, it is concerned with a device for moving a nozzle in a part cleaning device for washing the anus and functioning as a bidet and a method of controlling the position of the nozzle. The term "part cleaning device" as herein used means an apparatus including a tank for cleaning water, a cleaning nozzle which is movable between its retracted position and its cleaning position, a system for heating the cleaning water, a system for supplying the heated cleaning water, a system for moving the nozzle and devices for controlling those systems, and provided at the rear end of a water closet for directing a jet of heated cleaning water toward the private parts through the nozzle in its cleaning position.
2. Description of the Prior Art
In the part cleaning device, it is usually the case that the nozzle has two cleaning positions, i.e., the position for cleaning the anus and the position for functioning as a bidet.
There are known two arrangements for moving the nozzle forward from its retracted position to its cleaning positions and backward.
One of them relies on the pressure of cleaning water for moving the nozzle forward. The nozzle is slidably disposed in a cylinder and the cleaning water is introduced into the cylinder to push the nozzle out of the cylinder to either of its cleaning positions. A spring is connected to the nozzle for urging the nozzle back to its retracted position in the cylinder.
The other arrangement employs a motor which is rotatable in either direction for moving the nozzle out of, or into, a cylinder. This arrangement will hereunder be described with reference to FIG. 16.
The cylinder 101 is secured in a casing 100 located adjacent to the rear end of a toilet stool (not shown). The nozzle 102, which comprises a tubular body, is axially slidable in the cylinder 101. The electric motor 103 is provided adjacent to the proximal end of the cylinder 101 for moving the nozzle 102 forward or backward. The motor 103 has an output shaft 104 to which a cylindrical drum 105 is secured. A leaf spring 106 has one end wound on, and fastened to, the outer cylindrical surface of the drum 105. The other end of the spring 106 is connected to the proximal end of the nozzle 102. The output shaft 104 of the motor 103 is rotatable in two directions and the manner of the rotations of the output shaft 104 causes the reciprocal motion of the nozzle 102 in the cylinder 101. When the nozzle 102 is brought to its cleaning position, it directs a jet of cleaning water toward the private parts of a person using the toilet through its end openings 107. The positioning of the conventional nozzle 102 structure is effected by a feedback control system including a sensor of, for example, the magnetic or optical type which is located in a position for monitoring the motion of the nozzle 102. The sensor detects the amount of motion of the nozzle 102 and transmits a corresponding signal to the motor 103 to turn the power circuit of the motor 103 on or off.
The system relying on the pressure of the cleaning water for positioning the nozzle has the disadvantage that if the water pressure is lower than a predetermined level, the nozzle fails to reach its designated cleaning position and accomplish its proper cleaning function. If the nozzle is of the type having two cleaning positions for the anus and for the use as a bidet, respectively, its internal water passages formed in the nozzle 102 itself are complicated and the size of the nozzle 102 is undesirably enlarged.
The system employing the motor 103 for moving the nozzle 102 and the sensor for detecting and positioning it has the disadvantage that its nozzle positioning accuracy depends on the performance of the sensor. If the sensor fails to function accurately, the nozzle 102 fails to reach its designated cleaning position and also to accomplish its proper cleaning operation as mentioned above.
The sensor requires a complicated job of assembly including wiring connection between the motor 103 and the control system and mounting in a predetermined narrow space, and the control system also becomes complicated. The drum 105 has, as shown in FIG. 17, formed on its outer cylindrical surface a shoulder 108 and threaded holes 110 provided in the vicinity of the shoulder 108 for receiving screws 109 for securing the leaf spring 106. Thus, the outer cylindrical surface of the drum 105 on which the leaf spring 106 is wound does not have a uniform curvature. As the drum 105 is rotated alternately in the opposite directions, the leaf spring 106 is wound on the surface of the drum 105 and unwound therefrom repeatedly. Insofar as the surface of the drum 105 does not have a uniform curvature, with the passage of time the fatigue of the leaf spring 106 is not uniform along its length, and this causes stress concentration or buckling in the leaf spring 106 which leads to failure in driving the nozzle 102. The fastening of the leaf spring 106 to the drum 105 by the screws 109 adds to the amount of labor required for the fabrication of the apparatus and hence the cost thereof.
Another problem that the conventional part cleaning device involves is due to the fact that the distal end portion of the nozzle 102 which is provided with the openings 107 projects from the cylinder 101 even when the nozzle 102 is in its retracted position. The projecting distal end portion of the nozzle 102 is always liable to contamination by dirty liquid or matter, whether the nozzle 102 may be in its cleaning or retracted position. The dirty liquid and matter are likely to form powder on the projecting end portion of the nozzle 102 and in its openings 107 and thereby to block the openings 107. They have an objectionable odor, and contaminate cleaning water.